Note 5 - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jul. 01, 2016	Jun. 30, 2016	Jun. 30, 2015
Balance, Shares (in shares)	420,390	1,031,170	1,031,170	1,031,170
Balance, Weighted-Average Exercise Price (in dollars per share)	$ 23.80	$ 31.27	$ 31.27	$ 31.27
Balance, Weighted-Average Remaining Contractual Life	1 year 219 days	1 year 292 days	328 days
Balance, Aggregate Intrinsic Value	$ 2,026	$ 3,268	$ 3,268	$ 3,268
Exercised, Shares (in shares)		(2,110)		(2,110)	(73,350)
Exercised, Weighted-Average Exercise Price (in dollars per share)		$ 23.37
Forfeited, Shares (in shares)	(12,000)	(608,670)
Forfeited, Weighted-Average Exercise Price (in dollars per share)	$ 38.26	$ 36.46
Balance, Shares (in shares)	408,390	420,390		408,390
Balance, Weighted-Average Exercise Price (in dollars per share)	$ 23.37	$ 23.80		$ 23.37
Balance, Aggregate Intrinsic Value	$ 1,973	$ 2,026		$ 1,973
Exercisable, Shares (in shares)	408,390			408,390
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 23.37			$ 23.37
Exercisable, Weighted-Average Remaining Contractual Life	1 year 219 days
Exercisable, Aggregate Intrinsic Value	$ 1,973			$ 1,973